After Dengue Fever’s hot set at Emo’s, I was down to my final showcase of the festival as I pedaled over to La Zona Rosa on West 4th Street for a 12:45 AM set from Pretty Lights that I figured would close out the festival in maximum party style. The Colorado rock-tronica duo have been blowing up over the past year, winning raves while opening for Sound Tribe Sector 9 at Red Rocks last summer and becoming the hot new flavor in the livetronica scene.

The club was already hopping when I arrived, with the Crystal Method wrapping up what had clearly been a hot set of their own. Pretty Lights soon hit the stage and owned the crowd from the start, as DJ/synth master Derek Vincent Smith and drummer Cory Eberhard threw down one smoking hot groove after another with a spectacularly psychedelic light show behind them.

“Sunday School” was a scintillating jam, featuring a sampled vocal of “Fuck ’em, I didn’t want to go to heaven anyway” over a big trippy groove that had the whole room moving and grooving. It was a 75-minute dance party of block-rocking beats whose energy never waned as the set went right up until 2:00 AM. Some of the songs tended to sound kind of the same due to similar beats and tempos, perhaps suggesting Pretty Lights could go even higher by adding a guitarist. But there’s no doubt that this duo knows how keep a psychedelic dance party rocking.

“Finally Moving” closed out the festivities with a fresh bite on “All Along the Watchtower,” showing that there’s always another way to use the same three chords. Pretty Lights transformed the three-chord progression into a psychedelic down-tempo dance groove tricked out with all kinds of sonic bells and whistles for a dynamic 21st century remake of the classic groove. It was an elated crowd that wandered out into the night afterward. SXSW 2010 had just gone by in a flash, but it was hard to imagine a better ending.